Which would you rather have in real life
>Victini
+grants super powers and makes you win everything
-you will never see it and it has no emotional connection to you
>Manaphy
+can heart swap you into a different body
-you can only swap a particular pair of bodies once
>Jirachi
+grants infinite wishes
-completely hates you and will ignore wishes that are stupid or OP
>Celebi
+lets you time travel or distort time (speeding it up, reversing it, etc.)
-deceivingly happy and will send you to the dark ages if you piss it off
>Mew
+Will fight thieves and pretty much anything that tries to harm you in the night. it also enjoys all of its time with you
-Mew isn't immortal, and in the day it's essentially a telepathic cat.